# Modifying an RDS Custom for SQL Server DB instance to use a new CEV
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You can modify an existing RDS Custom for SQL Server DB instance to use a different CEV. The changes that you can make include:
+ Changing the CEV
+ Changing the DB instance class
+ Changing the backup retention period and backup window
+ Changing the maintenance window

## Console
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**To modify an RDS Custom for SQL Server DB instance**

1. Sign in to the AWS Management Console and open the Amazon RDS console at [https://console.aws.amazon.com/rds/](https://console.aws.amazon.com/rds/).

1. In the navigation pane, choose **Databases**.

1. Choose the DB instance that you want to modify.

1. Choose **Modify**.

1. Make the following changes as needed:

   1. For **DB engine version**, choose a different CEV.

   1. Change the value for **DB instance class**. For supported classes, see [DB instance class support for RDS Custom for SQL Server](custom-reqs-limits.instancesMS.md).

   1. Change the value for **Backup retention period**.

   1. For **Backup window**, set values for the **Start time** and **Duration**.

   1. For **DB instance maintenance window**, set values for the **Start day**, **Start time**, and **Duration**.

1. Choose **Continue**.

1. Choose **Apply immediately** or **Apply during the next scheduled maintenance window**. 

1. Choose **Modify DB instance**.
**Note**  
When modifying a DB instance from one CEV to an another CEV, for example, when upgrading a minor version, the SQL Server system databases, including their data and configurations, are persisted from the current RDS Custom for SQL Server DB instance.

## AWS CLI
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To modify a DB instance to use a different CEV by using the AWS CLI, run the [modify-db-instance](https://docs.aws.amazon.com/cli/latest/reference/rds/modify-custom-db-engine-version.html) command.

The following options are required:
+ `--db-instance-identifier`
+ `--engine-version cev`, where *`cev`* is the name of the custom engine version that you want the DB instance to change to.

The following example modifies a DB instance named `my-cev-db-instance` to use a CEV named `15.00.4249.2.my_cevtest_new` and applies the change immediately.

**Example**  
For Linux, macOS, or Unix:  

```
1. aws rds modify-db-instance \
2.     --db-instance-identifier my-cev-db-instance \ 
3.     --engine-version 15.00.4249.2.my_cevtest_new \
4.     --apply-immediately
```
For Windows:  

```
1. aws rds modify-db-instance ^
2.     --db-instance-identifier my-cev-db-instance ^
3.     --engine-version 15.00.4249.2.my_cevtest_new ^
4.     --apply-immediately
```